$width: 100px;
$height: $width + 100px;
div {
  background-color: red;
  width: $width;
  height: $height;
  .in {
    background-color: blue;
    width: 50px;
    height: 50px;
  }
  &:hover {background-color: green;}
  border: {
    style: solid;
    width: 1px;
    color: black;
  }
}

@mixin bordered {
  border-top: dotted 1px black;
  border-bottom: solid 2px black;
}
@mixin link-colors($normal, $hover, $visited) {
  color: $normal;
  &:hover { color: $hover; }
  &:visited { color: $visited; }
}
